The present invention relates to a pneumatic tire, more particularly to a unidirectional tread pattern suitable for racing, capable of improving steering stability and wear resistance on dry roads and drainage performance on wet roads.
In Japanese Patent Application Publication No. 2009-23654, a pneumatic tire having a tread pattern shown in FIG. 5 is disclosed as being capable of improving the tread wear life, without sacrificing steering stability in dry conditions and wet conditions.
In this tread pattern, main oblique grooves (b) are disposed staggeredly on both sides of the tire equator (a), and the main oblique groove (b) extends toward the opposite direction CR to the intended tire rotational direction from a starting point (b1) near the tire equator to a position outside the tread edge (E), while describing a convex curve having a specific curvature.
Between every two of the circumferentially-adjacent major oblique grooves (b), one minor oblique groove (c) is disposed so as to incline to the opposite direction CR to the intended tire rotational direction.
The axially outer end of the minor oblique groove (c) is closed at a position axially inside the tread edge E.
Such tire may exhibit good drainage performance on wet roads covered with water whose depth is relatively shallow. But, on wet roads covered with deep water, the axially outer ends of the minor oblique grooves (c) are submerged in the water, therefore, sufficient drainage can not be obtained. Thus, there is room for improvement in the drainage performance especially on the wet roads covered with deep water.
Further, at the starting point (b1), the minor oblique groove (c) intersects with the major oblique groove (b).
As a result, a tread part between the minor and major oblique groove (c and b) is decreased in the rigidity disadvantageously to the steering stability and wear resistance on dry roads. Thus, there is room for improvement in the steering stability and wear resistance on dry roads.